Electron collision strengths for the far-infrared lines of O III

New collision strengths for electron impact excitation of the $$^{3}\text P_{3}\rightarrow ^{3}\text P_{J'}$$ fine structure transitions within the ground configuration of O⁺⁺ are presented. These were obtained by using a suitable transformation of LS-coupling reactance matrix elements computed with the well-known R-matrix method. The results exhibit a complex pattern of resonances and are given graphically for electron energies below 7.36 eV. The thermally averaged collision strengths (from which rate coefficients can readily be determined) have been evaluated and are tabulated as functions of the electron temperature in the range 0 ≦ T_e ≦ 2 × 10⁴K.